Date: Fri, 2 Feb 2007 13:48:31 +0100 From: J65nko <j65nko@gmail.com> To: Tigger <tigger@lvlworld.com> Cc: freebsd-questions@freebsd.org Subject: Re: unexpected result from sh script with `date` Message-ID: <19861fba0702020448u50ac68adqf205a3cd001e901f@mail.gmail.com> In-Reply-To: <20070202111156.GA41151@lilypie.com> References: <20070202111156.GA41151@lilypie.com>
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On 2/2/07, Tigger <tigger@lvlworld.com> wrote: > Hello, the following simply sh script is outputting unexpected results. > Any idea why? > > --script-- > > #!/bin/sh > > started=`date` > > echo "Started at: $started" > echo "Finished : "`date` > exit > > --output-- > > Started at: Fri Feb 2 22:13:51 EST 2007 > Finished : Fri Feb 2 22:13:51 EST 2007 > > --problem-- > > Between 'Feb' and '2', there is two spaces on the 'Started at' line, > however the 'Finished' one only has 1 space. > > I know this sounds picky, but I was not expecting this at all. > > uname -a > FreeBSD piglet 6.2-STABLE FreeBSD 6.2-STABLE #0: Fri Jan 19 04:13:20 EST > 2007 tigger@piglet:/usr/obj/usr/src/sys/PIGLET i386 The same on OpenBSD here (ksh) OpenBSD 4.0-current (GENERIC) #1194: Thu Nov 2 16:32:12 MST 2006 deraadt@i386.openbsd.org:/usr/src/sys/arch/i386/compile/GENERIC It seems to depend whether the command substitution is within the quote-delimited string, for 'echo' or outside that string, in other words on its own. ------- script---------- #!/bin/sh started=$(date) echo "\$started within \" delimited string for echo" echo "Started at: $started" echo "Command substitution \$(date) within \" delimited string for echo" echo "Finished : $(date)" echo "Command substitution \$(date) outside \" delimited string for echo" echo "Finished : "$(date) echo "Command substitution \`date\` outside \" delimited string for echo" echo "Finished : "$(date) ----------------------------------- Output: ------------------- $started within " delimited string for echo Started at: Fri Feb 2 13:46:07 CET 2007 Command substitution $(date) within " delimited string for echo Finished : Fri Feb 2 13:46:07 CET 2007 Command substitution $(date) outside " delimited string for echo Finished : Fri Feb 2 13:46:07 CET 2007 Command substitution `date` outside " delimited string for echo Finished : Fri Feb 2 13:46:07 CET 2007 --------------------------------------- Embedded inside the string there are two spaces between Feb and the 2, as "stand-alone" there is only one space. Strange indeed ;) J65nko
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